Methods of conditioning shoe uppers



April 6, 1965 M. MAESER 3,176,333

METHODS OF CONDITIONING SHOE UPPERS Filed Sept. 17, 1963 2 Sheets-Sheet1 \isted At Foam 7mpemture After Storage In Super Hea Zed Steam AZ @50 6En! Minute 0 I I I l l I l l I Water CmZent flzflry Wt.

Aft $z0ra9e [21 Super Heated Steam Ai'250C fbrlMim/ie Tsted At Room 7m0erature Inuenfm" Mei/L Naeser' 0 5 hi H0 Water Content- ZZZ y Wt.

.DAsCort/on 0n Grain CraC/f-INC/I A ril 6, 1965 Filed Sept. 17, 1963Permanent Set 7o/70/ded Dept/'1 M. MAESER 3,176,333

METHODS OF CONDITIONING SHOE UPPERS 2 Sheets-Sheet 2 l E 9 After StorageIn Super Heated Steam At 250 "c fErZM/nule 7sted At fioom 7e'mpera tureWater Content 7, Dry Wt.

Leather Hav/M ZJZ Water Lea ther Haw n9 1. We zer' Umforml yDz'sZribuZed Throughout Dry Oven300F l I I I 5f;- 0 Dry Oven Z50F DryOver: 850/ Fme In 0ven-Mirwfes- United States Patent 3,176,333 PatentedApr. 6, 1965 nice 3,176,333 METHUDS F CONDITHONING SHOE UPPER? MiethMaeser, Beveriy, Mass, assignor to United Shoe Machinery Corporation,Flemington, NJL, a corpora tion of New Jersey Filed dept. 17, 196.3,Ser. No. 309,417 23 Qlaims. (Ci. 12-142) This invention relates to aprocess of conditioning leather and, more particularly, to a method ofcondition ing upper leather comprising an improved method of mullingprior to lasting and a novel method of setting subsequent to lasting,this application being a continuation-in-part of an application SerialNo. 253,833, filed January 25, 1963, in the name of Mieth Maeser, nowabandoned.

The conditioning of upper leather is a problem which has plagued thesboemaking industry throughout the years. Numerous attempts have beenmade to solve the problem but until the subject invention no solutionwas forthcoming which improved the characteristics of leather importantto lasting to the maximum degree possible and also accomplished the setrequired in a minimum period of time. Proper conditioning of leather isof paramount importance not only to the quality of the finished shoe butalso to the workability of the leather during the manufacture thereof.In order to facilitate the lasting of a shoe, the flexibility andstretchability of the upper leather must be increased. Accordingly, thevalue of a method of conditioning upper leather prior to lasting islargely determined by the degree to which it increases the abovenotedcharacteristics. However, the lasting of a shoe upper involvesprincipally the stretching and compressing of the leather and,therefore, the characteristic of stretchability takes precedence inselecting the method of conditioning. Thus, the problem of prelastingconditioning is to devise a method of mulling which attains maximumstretchability and also increases the flexibility a'maximum amount basedupon a stretchability increase.

The setting of a shoe upper subsequent to lasting affects the quality,durability, wearability and appearance of the finished shoe. Themoisture imparted to the upper leather during prelasting conditioningmust be removed in suflicient quantity to place the leather in normalcondition and the leather must be set in the configuration imposed bythe last. The quality and degree of set attained determines the lengthof time the shoe will remain in the configuration originally impartedthereto. The principal end to be accomplished in the setting of a shoeupper is the relief of any stresses existing within the leather prior tolasting and those induced by lasting thereby to permit the shoe toassume the configuration desired without contrary'r'esidual stresses ormemory. The appearance of the shoeis also affected by the shrinkage ofthe upper leather on the last. A method of setting should permit thatamount of shrinkage necessary to impose the last configuration into theleather and eliminate wrinkles therefrom but must not result inexcessive shrinkage whereby the leather is damaged or marred.

. A further problem which pervades conditioning of leather inthemanufacture of shoes is the economic aspects of the conditioningprocess.- The duration of the conditioning operations determines thenumber of lasts the manufacturer must employ. A conditioning methodwhich markedly shortens the period of time a shoe must remain on thelast enables a manufacturer to reduce the number of lasts being utilizedthereby diminishing the overall cost. of making the shoe. Further,proper prelasting conditioning facilitates an increase in the speed andefliciency of the lasting operations and, thus, considerable costsavings.

In view of the foregoing, an object of the present invention is toprovide a method of conditioning upper leather which places the leatherin a condition of maximum stretchability and correlated flexibilityprior to the lasting operations and which attains optimum set of theupper leather after lasting thereof has been completed.

A further object of this invention is the attainment of the above-notedends in a minimum period of time consistent with quality shoemanufacturing standards.

To this end and in accordance with a feature of the present invention,there is provided a method of shoemaking comprising subjecting a leatherupper to a humidified atmosphere to distribute water uniformlythroughout the upper leather, heating the leather upper in hightemperature moist air, lasting the leather upper while it is moist andat a high temperature, heating the lasted upper in a moist atmosphere,and drying the lasted upper v in a dry atmosphere.

An alternative specie of the above method is also provided wherein theheating and drying completed subsequent to lasting are performed in asingle high temperature moist atmosphere.

The above and other features of the invention will now be described, theaccompanying drawings being included to aid in the delineation thereof.

FIG. 1 is a cross-sectional view of a piece of leather;

FIG. 2 is a graph illustrating the effect of moisture and temperature onthe stiffness of leather;

FIG. 3 is a graph illustrating the effect of moisture and temperature onthe distortion at grain burst, and, thus, on the stretchability of thegrain; V

FIG. 4 is a graph illustrating the effect of moisture and temperature onthe distortion at total burst and, thus, on the stretchability ofleather; and

FIG. 5 is a graph illustrating the effect of moisture and temperature onthe permanent set,

In order to appreciate the advantages of the present invention ananalysis of certain characteristics of leather must be made and theeffect thereof on conditioning weighed. As illustrated in FIG. 1, aleather skin comprises a grain area 10, a corium l2, and a mucoid layer14. The mucoid layer 14 is primarily a bonding between the grain and thecorium and is of little significance to the structural properties ofleather. The grain area 10 has approximately one half the tensilstrength of the corium 12. Therefore, when a leather upper is overworkedthe grain layer ruptures first. However, in the. normal leathercross-section the greatest portion is composed of corium fibers and,thus, this area is of primary significance in conditioningv the leather.As noted above, the lasting of a leather upper involves principally thestretching and compressing of the fibrils of the leather. Theflexibility of the leather is significant in that it must be increasedto permit that flexing resulting from lasting over the feather line andto prevent cracking of the grain area but it is of secondary importanceto an increase in stretchability.

The graphs of FIGS. 24 illustrate the eflects of moisture upon leather.Immediately upon the application of moisture to the surface fibers ofthe leather, the flexibility of the grain is increased and, therefore,the flexibility of the entire member. When the moisture is confinedprimarily to the grain area, stretchability of the grain area per seisincreased. However, this increase in the stretchability of the grainarea is of negligible significance to the overall workability of theleather as a result of the condition of the corium. Thisis. equally truewhen moisture is applied and confined to the grain and the outer surfaceof the corium disposed from the grain as the effeet on the total coriumarea is minimal. If the total moisture content of the leather upperremains approxi perature moist atmosphere.- 7 g V moist atmosphere,shouldbe between140 F; and SOO.

mately'constant, maximum flexibility exists when the ability isincreased due to the permeation of the corium by the moisture. Thus, anend to be attained by arnethd of conditioning prior to lasting is thedlstributionof moisture throughout.'the leather and sufi'icientconcentration of moisture in the grain area to permit flexing during thelasting operations. V p

The application of heat has a marked influence on the mulling ofleather, as illustrated in FIGS. 24'. Heat lowers the viscosity andsurface tension'yof liquid and enables it to penetrate the surface morereadily. Further, the heat acts to soften the moist fibrils of theleather thereby to increase the workability thereof. Thus, heat is animportant adjunct of moisture in the conditioning ofleatherr V As statedabove, the primary ob ective in the setting of leather subsequent tolasting-is the relief ofresidual stresses and memory and'the impositionofstresses and configuration imparted theretoby the lasting operations.

memory therein if the method is successfully to set the upper leather inthe desiredshape. The combination of} moisture and heat have a stressrelieving effect on leather. The graphs of FIG. 5 illustrate theinfluence of moisture and heat on the. setting of leather. Withsufficient moisture present in the leather heat is able to reach themoisture and soften the fat liquors and fibers of the: grain and coriumthereby to allow maximum movement of the fibers. As a result, theinternal stresses caused by resid-' ,memory which tend to retain theupper leather. in the .magnitude sufficient to insure at least moistureequilibrium between the atmosphere and the leather thereby to preventdrying of the leather. This is accomplished by maintaining the dew pointof the atmosphere above the temperature of the upper leather. The resultof this step is to precipitate a film of water on the surface or grainof the leather. The presence of the upper in the heated atmospherecondenses this Water film and the heat of condensation results in rapidheating of the upper. Further, since a moist surface will pickup moreheat than a dry surface the rate of heating of the upper leather will beincreased until the surface of the grain is dry. 'Ifhe result of theabove is that water is distributed throughout the leather, moisture isconcentrated in the grain'area below the surface thereof and the leatheris rapidly brought to the desired temperature level.

After the lasting operations have been completed, the

shoe is again heated in a high temperature moist atmosphere; .Thetemperature of the atmosphere should preferably be above the boilingpoint in the 220,? F. to 375 F; range'andthe dew point of the atmosphereabove the temperatureof the shoe. As explained above, this facilitatesrapid heating of the upper leather Without removing the moisturepreviously imparted thereto thereby providing the combination ofmoisture and heat required for stress relief. Further, this heating stepis accomplished without adding an appreciable amount of moisture as the15 to 25% moisture content already in the leather'upper representssubstantially the maximum saturation which can be obtained under theconditions involved. This step normalizes the. leather thereby relievingthe residual 'stresses referredto above. The temperature oftheatmosphere should be regulated for a parual tanning effects, finishing,and pulling and lasting'are released and the residual memory dissipatedthereby nor- I I thev configuration imparted'by the last and to lock'themalizing the fibers of the grain and corium and. preparing theleatherfor the imposition of retaining stresses to remove excessivemoisture: and impose retaining stresses and memory. The drying alsoserves to shrink the upper whereby the upper is subjected to theconfigu-' and position, is subjected to a greateramount ofheat and,accordingly, shrinks more than other portions-of'the V 7 ration of thelast. The grain .area,'due to its relative s1ze,

ticular leatherto insure that the grain of the leather is not lifted :ormade rough. The purpose of this step "is to heat the leather, not to dryit. I

The final. step in the method of this invention is to draw the'moistureout of the leather to set the upper in leather in the new shape byheating infa dry atmosphere, preferably at a temperature above theboilingpoint, of .water. .The, resultof this last operation is toimparta new memory to the leather'which tiesthe fibers in the new shapeimposed 'by the last. The" combination, of temperature and' timerequired to dry the leather should be such that the excess moistureiscompletely removed, the creep tendencies dissipated, the wrinkleschased" and memory leather thereby resulting inthe elimination ofwrinkles in the surface thereof. The time permitted for drying isimportant not only with respect to the economic production of shoes butalso in that it must be of suflicient'duration to permit the negationofcreepwithin theupper. A

methodv which attempts to solve the problem of rapid drying by applyingmoisture only to'the surface areas or grain of theleather and removingthe same before it' 'permeates'the corium, failstoitakeadvantage of thestretchability characteristics of the corium and, further,

has no eifect on thestresses' and memory of the corium. In theapplication of the method of thefsubject invention a leather upper isinitially mulledin a humidified atmosphere to distribute water'uniformlythroughout the grain and corium of the upper leather. The normalmoisture content of leather is between 8% and 11%. The

object of the mulling operation is to increase the moisture content to15 to 25%.; This. operation insures that the leather will be of maximumstretchability prior to the lastingoperations. After the mullingoperation is imposed.- Thejend accomplished by this operation can beattained bymerely permitting exposure of the upper to the surroundingatomsphere for a sufiicientperiod of time. Howeveryheating thereof in-a.dryatmosphere reduces the time required for setting and resultsin betterset.

The'two steps of the above described method performed subsequent tolasting may,tin the alternative, be combined into aunltarystep-employing a singleatm'osphere to both 7 heat anddry 'the lastedupper. This-is accomplished by the use of a high; temperature moistatmosphere the dew pointand temperature of which are controlled 'suchthat, fora given exposure interval, the temperature of the exposed.upper is elevated from a level belowthe' dew point toa levelthereabove. In thepractice of this alternative specie, an upper isintroduced to a humidified atmosphere havin g a dew point above theinitial temperature of the upcompleted, the leather upper-is heated in ahigh tem-z' The temperature of the but preferably would be in the 250 F.10300 F.

range. This step in the method is actually a heating f temperaturethereof is raised without withdrawing moisture therefrom. Theexposurekinterval is regulated such that the temperature of thehpperisraised above the ,dew

-- pointeof the atmosphere therebyjresulting invmoisture re {moval fromthepupper thereafter. a Ergo, a single humidi fied l atmosphere "isutilized to heat the .moistrupperrthere- .byto relievetheresidualstresses therein and to dry the .uppertherebyfto set the upper-in theconfiguration im- ".PartedbYthelast. J

seribed; invention; what I claim as Having thus de new and desire tosecure by Letters Patent of the United States is:

1. The method of setting a moistened shoe upper on a last subsequent tocompletion of all the lasting operations to impart to said upper apermanent reproduction of the shape of the last comprising heating theupper in a moist atmosphere while the upper is on the last thereby toheat the moisture and fat liquors in the upper to soften the fibers ofthe grain and of the corium to relieve stresses in said fibers withoutadding an appreciable amount of moisture to the upper and subsequentlydrying the upper while on the last in a high temperature dry atmosphereto remove moisture therefrom and thereby impart stresses to the fibersof the grain and of the corium of the upper which thereafter produce apermanent reproduction of the shape of the last.

' 2. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to raise the moisture content thereof to 15% to 25uniformly distributed throughout the upper leather, heating the upperleather in 140 F. to 300 F. moist air, said moist air having a dew pointabove the temperature of the upper leather, lasting the leather upperwhile said upper is at a high temperature and moist, heating the lastedupper in a moist atmosphere, said moist atmosphere being in thetemperature range of 220 F. to 375 F. and having a dew point above thetemperature of the upper leather, and drying the lasted upper in ahigh-temperature dry atmosphere.

3. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to raise the moisture content thereof to 15% to 25uniformly distributed throughout the upper leather, heating the upperleather in 140 F. to 300 F. moist air, lasting the leather upper whilesaid upper is at a high temperature and moist, heating the lasted upperin a moist atmosphere, said moist atmosphere being in the temperaturerange of 220 F. to 375 F., and drying the lasted upper in ahightemperature dry atmosphere.

4. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to raise the moisture content thereof to 15% to25% uniformly distributed throughout the upper leather, heating theupper leather in high-temperature moist air, said moist air having a dewpoint above the temperature of the upper leather, lasting the leatherupper while said upper is at a high temperature and moist, heating thelasted upper in a moist atmosphere, said moist atmosphere having a dewpoint above the temperature of the upper leather, and drying the lastedupper in a high-temperature dry atmosphere.

S. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to distribute water uniformly throughout the upperleather, heating the upper leather in high temperature moist air, saidmoist air being in the temperature range of 140 F. to 300 F. and havinga dew point above the temperature of the upper leather, and lasting theleather upper while said upper is still moist and at a high temperature.

6. The method of conditioning upper leather subsequent to lastingcomprising heating the upper in a moist atmosphere, said atmospherebeing in the tempenature range of 220 F. to 375 F. and having a dewpoint above the temperature of said upper, and drying the upper in ahightemperature dry atmosphere.

7. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to raise the moisture content thereof to 15% to 25uniformly distributed throughout the upper leather, heating the upperleather in high-temperature moist air, said moist air being in thetemperature range of 140 F. to 300 F., and lasting the leather upperwhile said upper is still moist and at a high temperature.

8. The method of conditioning upper leather subsequent to lastingcomprising heating the upper in a moist atmosphere, said atmospherebeing in the temperature 0 range of 220 F. to 375 F., and drying theupper in a high-temperature dry atmosphere.

9. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to distribute water uniformly throughout the upperleather, heating the upper leather in high-temperature moist air, saidmoist air having a dew point above the temperature of the upper leather,and lasting the leather upper while said upper is still moist and at ahigh temperature.

10. The method of setting a moistened shoe upper on a last subsequent tocompletion of all the lasting operations to impart to said upper apermanent reproduction of the shape of the last comprising heating theupper in a moist atmosphere while the upper is on the last thereby toheat the moisture and fat liquors in the upper to soften the fibers ofthe grain and of the corium to relieve stresses in said fibers withoutadding an appreciable amount of moisture to the upper, said atmospherehaving a dew point above the temperature of said upper, and subsequentlydrying the upper while on the last in a high temperature dry atmosphereto remove moisture therefrom and thereby impart stresses to the fibersof the grain and of the corium of the upper which thereafter produce apermanent reproduction of the shape of the last.

11. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to distribute water throughout the upper leather,heating the upper leather in high-temperature moist air, said moist airbeing in the temperature range of F. to 300 F., lasting the leatherupper while it is still moist and at a high temperature, and heating thelasted upper in a moist atmosphere, said moist atmosphere being in thetemperature range of 220 F. to 375 F.

12. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to distribute Water throughout the upper leather,lasting the leather upper while said upper is moist, and heating thelasted upper in a moist atmosphere, said moist atmosphere being in thetemperature range of 220 F. to 375 F.

13. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to distribute water throughout the upper leather,heating the upper leather in high-temperature moist air, said moist airbeing in the temperature range of 140 F. to 300 F. and having a dewpoint above the temperature of the upper leather, lasting the leatherupper while it is still moist and at a high temperature, and heating thelasted upper in a moist atmosphere, said moist atmosphere being in thetemperature range of 220 F. to 375 F. and having a dew point above thetemperature of the upper leather.

14. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to distribute water throughout the upper leather,lasting the leather upper while said upper is moist, and heating thelasted upper in a moist atmosphere, said moist atmosphere being in thetem erature range of 220 F. to 375 F. and having a dew point above thetemperature of the upper leather.

15. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to add water throughout the upper leather, heatingthe upper leather in high-temperature moist air, said moist air having adew point above the temperature of the upper leather, lasting theleather upper while it is still moist and at a high temperature, andheating the lasted upper in a moist atmosphere, said moist atmospherehaving a dew point above the temperature of the upper leather.

16. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to add Water throughout the upper leather, lastingthe leather upper while said upper is moist, and heating the lastedupper in a moist atmosphere, said moist atmosphere having a dew pointabove the temperature of the upper leather.

17. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to raise the moisture content thereof to 15 [to 25uniformly distributed throughout the upper leather, lasting the upperwhile said upper is moist, heatingthe lasted upper in a i moistatmosphere to relieve the stresses therein and drying the lasted upperin a high-temperature, dryatmosphere.

18. The method of setting a'moistened leather shoe up-- I per on a lastsubsequent to completion of all'the lasting I operations to impart tosaid upper a permanent reproduction of the shape of the last comprisingexposing the upper to a high-temperature moist atmosphere having a dewpoint above the initial temperature of the upper, thereby 21." Themethod of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to add moisture throughout the upper, 'heating'the upper in a high temperature moist atmosphere, lasting the I upperwhile said upper is at a high temperature and moist, heating the upperin a high' temperature moistatrn'osphere, said atmosphere having adewpoint above the temperature of the upper prior to exposure to saidatmosphere, maintaining the up- Y per exposed to said atmosphere, for aperiod sufficient to to heat the moisture and fat liquors in theupper tosoften the fibers of the grain and a of the corium to j relieve stressesin said fibers without adding an appreciable amount of moisture to theupper and maintaining theupper exposed to said atmosphere for a periodsui ficient to 1 raise the temperature of the upper above'the .deWpointof the atmosphere thereby to drythe upper-to impart raise thetemperature of the upper above the dew point of the atmosphere," anddrying the upper by exposure to said atmosphere subsequent to thereversal, of the relative V magnitude of saiddew point and temperature.

22. The method of setting a moistenedshoe upper on a last subsequent-tocompletion of all the lasting operations, to impart to said upper apermanent reproduction stresses'tovthe fibers of the grain and of thecorium of j the upper which thereafter produce a permanent reproduc tionof the shape of thelast, r

19. The method of setting. a moistened shoe upper on a' last subsequentto completion of all the lasting operations to impart to said upper apermanent reproductionof the shape of the last comprising heating theupperin a high-temperature moist atmosphere while the upper is on thelast thereby to heat the moisture and the fat liquors to soften thefibers of the grain and of the corium and torelieve' stresses in saidfibers. without adding an] appreciable'amount of moisture to the upper,said atmossequentlydrying the upper; while on the last by exposure toature of theiupper above the dew point of the atmosphere thereby to heatthe moisture and fat'liquors in the upper of the shape of the lastcomprising heatingthe upper in a high temperature moist atmospherehaving a dew point above the temperature of the" atmosphere prior to'exposure thereto for a period suflicient to raise the temperto softenthefibers of the grain and 'of the corium to relievestresses in, saidfibers without adding an appreciable phere having a dew point above theinitial temperature of e amount of'moisture to the upper, saidatmosphere being in the temperature range of 200 F; tot300 F., andthereafter drying the upperin said atmosphere to impart stresses to thefibers of thetgrain and of the corium of the upper which thereafterproduces a permanent' reproduction of the shape of the last.

23. The method of shoemaking comprising subjecting a leather upper to ahumidified atmosphere to raise the said atmosphere subsequent to thereversal ofthe relative I magnitude of said dew point and temperaturethereby to 1 Qimpart stresses to the fibers of the grain and of thecorium of the upper which thereafter produce a permanent l -F., andthereafter drying the upper in saidatmosphere.

reproduction of the shape of the last.

20. The method of shoemaking comprising subjecting a leather upper to ahumidifiedatmosphere to add moisture throughout the upper, lasting theupper while said upper is moist, heating the upper in :a hightempenature'moist atmosphere having a dew point above the temperature ofi moisture content thereof to 15% to 25 uniformly distributed throughoutthe upper leather, lasting the upper while said upper; is moist, heatingthe upper-in a high temperature moist atmosphere having a dew pointabove the temperature of the upper priorto expos'ure thereto "for aperiod suflicientfto raise the temperature of. the

the upper prior toexposure thereto for a period sufficient to raise thetemperature of the upper above therdew point atmosphere.

' of the atmosphere,- and thereafter drying the upper in said upperabove the dew point oftheatmosphere; said atmosphere 'beingin thettemperatureirange of220 F. to 375 References Cited the Examiner UNITEDSTATES PATENTS 2,973,530 3/61 nmmaa 12 -142 iJoRD N FRANKLIN, PrimaryEt'a iaer.

9. THE METHOD OF SHEOMAKING COMPRISING SUBJECTING A LEATHER UPPER TO AHUMIDIFIED ATMOSPHERE TO DISTRIBUTE WATER UNIFORMLY THROUGHOUT THE UPPERLEATHER, HEATING THE UPPER LEATHER IN HIGH-TEMPERATURE MOIST AIR, SAIDMOIST AIR HAVING A DEW POINT ABOVE THE TEMPERATURE OF THE UPPER LEATHER,AND LASTING THE LEATHER UPPER WHILE SAID UPPER IS STILL MOIST AND AT AHIGH TEMPERATURE.